#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=3e5+1000;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
char a[maxn];
int main(void){
   cin.tie(0);std::ios::sync_with_stdio(false);
   LL n;cin>>n;
   cin>>(a+1);
   LL pre=1;
   LL ans=0;
   for(LL i=2;i<=n;i++){
      if(a[i-1]!=a[i]){
         ans+=(i-pre);
         pre=i;
      }
      else if(pre!=1) ans++;
   }
   cout<<n*(n-1)/2-ans<<"\n";
   return 0;
}
